Lift Z usage

I have (multiple) objects where I would like to raise the nozzle a bit for long fast moves crossing perimeters that have cooled already a bit due to long layer print time.
Sometimes the nozzle will hit the object in the same layer where already printed.

I was wandering if this is what the "Lift Z" function does while retract is triggered ?

So I can define a travel for which Z is raised (build plate lowered), than the travel takes place and at the end of the travel, the Z is lowered again as is the retract ? ?


Thanks, Thomas

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)

Yes. You can also use the "avoid crossing perimeters" option which will steer the nozzle around already completed part on the same layer. It tends to slow down the printer because the travel times increase.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Thanks. I will experiment with both options :-)

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)

I have sliced with the Lift Z before... where I defined a travel distance.
This really improves travel to perimeters that tend to crawl up. Now it does not crash into th eperimeter but stops abve it and lowers into it nicely.

However, a home-x command, which I will have inserted by the custom code 'after layer change' does travel a lot more , but does not trigger the lift z.

So the home action might still crash into a perimeter during the home travel.

Any thoughts ?

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)

Command a G1 X0 before the home?

hmm... would that result in the same travel as G28 x0 ?
If so, I can replace the homings ...

I wil try thanks

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)

G1 goes to the specified coordinate (in this case X = 0) with whatever tool offset you have configured taken into account.

G28 goes towards the endstop until it hits it and re-establishes the coordinate system.

Unless you're doing something with the machine by hand that could result in turning motors so the axis isn't where it thinks it is or you absolutely need the carriage as far as it can be off the print bed, homing during a print may not be optimal, as it introduces one more thing that could cause layer shifts if it doesn't home exactly the same way every time.

Wait...It's not the firmware you need to trick into viewing that as a travel move...It's Slic3r, and that probably doesn't review your custom G-code to see if a Z-lift is appropriate...Sorry, wasn't thinking right about that. You can add the following to your after-layer-change gcode, or if you do it before the layer change you wouldn't need the move back down because the move to the new layer will position the nozzle appropriately:

G91 ; change to relative positioning
G1 Z1 F2000 ; move up 1 mm
G28 X0
G1 Z-1 F2000 ; move down 1 mm
G90 ; change to absolute positioning

Change the dimension as you see fit.

Mind if I ask why you're homing on layer change?

Thanks. That looks promising

On your question... Yes you may ask
Every now and then, my printer looses some steps in the X direction.
The result being a completely ruined object, displaced from the layer that missed the step.

Some are deductable to hitting a perimeter during long travel (that why I am experimenting with the Z-lift)
However, some are not explainable. As diagnosing has not yet been succesfull, I am now homing after each layer (which takes not long).
This will render a missed step layer to only that layer being displaced. The printer is 'forgivving' for that layer when the rest is ok again after the home.
(Only need to clean up the one layer debris)

Maybe I can skip the homing in future, when Z-lift works for me as advised.

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)

Your printer has a problem that needs to be fixed, not worked around. 3D printers are already so full of problem work-arounds for poor design and cheapness that it's ridiculous. Find the problem and fix it.

The moving mass of the X axis is lower than the moving mass of the Y axis in most Cartesian printers. If layer shifts occur in X but not Y, that points to a mechanical problem with the X axis. Start by taking off the belt and make sure the carriage slides smoothly and easily from one end of the X axis to the other. If it binds or is hard to move or inconsistent, fix the problem. If that's OK, check the pulley on the motor and make sure it is screwed on tightly. If that is OK, reconnect the belt and make sure it doesn't rub on anything and that it runs parallel to the X axis.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Yes,
it has a problem, I am aware of that.Thankyou for pointing that out
But while finding time to fix it, I would like to keep printing in mean time. That's why the work around homing X is applied.

The lift Z is usefull anyhow, for other reasons too

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)

X-homing is unlikely to result in exactly the same position each time, and so homing between each layer will almost certainly result in ragged layers. As the PP has said, you will be far better off to resolve the real problem sooner rather than later - I suspect you have spent more time on refining your workaround than it would have taken to fix the real issue.

If the nozzle is hitting parts of the print, this will be due to excessive blobbing (try bigger/faster retraction and/or slower print speed), or curl-ups (reduce overhangs or provide better cooling for those areas). Other causes for missed steps is too much acceleration, which you might be able to correct in your start code if the printer's firmware supports acceleration parameters.

Dave

Edited 1 time(s). Last edit at 08/31/2016 08:06AM by dmould.

My new bearrings have arrived,
So I will start rebuilding the x-carriage with new bearings. I get the idea there is some drag in them now that might cause the step failure

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www.3daybreaker.blogspot.com

Orca V4.4 rebuild to Ramps with Mk8 and E3D, as well as a Rostock Delta Mini and an OLO in backorder :-)